The process of meiosis and ascospore development in the yeast Saccharomyces cerevisiae will be investigated. Mutants affected in the ability to undergo the developmental process at high temperature will be isolated. The nature and amount of transcription which occurs during sporulation will be investigated, or will change in the RNA polymerase complement of meiotic cells. BIBLIOGRAPHIC REFERENCES: Magee, B.B., J. Paoletti, and P.T. Magee. Separation of lymphocyte chromatin into template-active fractions with specificity for eukaryotic RNA polymerase II or prokaryotic RNA polymerase. Proc. Nat. Acad. Sci. (Wash.) 72:4830-4834 (1975). Heywood, P., and P.T. Magee. Meiosis in microorganisms. Some structural and physiological and genetic aspects of meiosis in algae, fungi, and protozoa. Bacteriol. Reviews. In press (March, 1976).